Brake rotor

ABSTRACT

A brake rotor including a rotor support; and a braking band disposed on and encircling the rotor support. The braking band has first and second brake pad receiving surfaces on opposite sides of the braking band. At least one brake pad receiving surface defines at least one groove that has a groove path extending along and having a variable depth with respect to the at least one brake pad receiving surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No. 12/959,740 filed Dec. 3, 2010, the entire contents of which are expressly incorporated herein by reference thereto.

TECHNICAL FIELD

This disclosure relates to brake rotors.

BACKGROUND

Disk brakes are commonly used for slowing or stopping the rotation of a wheel of a vehicle. Generally, a disk brake system includes a rotor connected to the wheel and/or an axle of the vehicle and a caliper. The caliper houses brake pads on opposite sides of the rotor and pistons that move the brake pads into frictional contact with the rotor to slow or stop rotation of the rotor. Usually rotors are made of cast iron or ceramic composites (including carbon, Kevlar and silica). In addition, the caliper is generally actuated hydraulically to move the pistons between braking and non-braking positions. Other methods of caliper actuation include mechanical linkage systems, pneumatics, and electromagnetism.

SUMMARY

One aspect of the disclosure provides a brake rotor including a rotor support (e.g., a mounting bell) and a braking band disposed on and encircling the rotor support. The braking band has first and second brake pad receiving surfaces on opposite sides of the braking band. At least one brake pad receiving surface defines at least one groove that has a groove path extending along and having a variable depth with respect to the at least one brake pad receiving surface.

Implementations of the disclosure may include one or more of the following features. In some implementations, the at least one brake pad receiving surface defines non-intersecting asymmetrical grooves arranged asymmetrically with respect to each other. In additional implementations, the at least one brake pad receiving surface defines groups of non-intersecting asymmetrical grooves. Each groove of the groove group has a groove path along the at least one brake pad receiving surface different from any other groove of the respective groove group. Each groove group can be arranged asymmetrically circumferentially about the at least one brake pad receiving surface.

In some examples, each groove group comprises first, second, and third grooves, each groove disposed in respective first, second, and third groove regions of the at least one brake pad receiving surface arranged circumferentially with respect to each other about a center axis of rotation defined by the brake rotor. Each groove region may have a radial width of about ⅓ of a radial width of the at least one brake pad receiving surface. Moreover, each groove group can be sized to reside completely with a perimeter of an engagement surface of a received brake pad.

In some implementations, each groove path has first and second radii of curvature for corresponding first and second curves along the at least one brake pad receiving surface. In some examples, the first and second radii of curvature are equal.

The first and second brake receiving surfaces may each have inner and outer diameters with respect to a center axis of rotation of the brake rotor. Each groove path may extend along the at least one brake pad receiving surface at a groove distance from the center axis greater than or equal to one half of the inner diameter of the brake receiving surface having the largest inner diameter among the two brake receiving surfaces, plus a clearance distance. In some examples, the clearance distance is about 0.18 inch and the rotor support has a height of less than or equal to 3 inches. The rotor support height is measured as the overall height of the brake rotor minus the overall thickness of the braking band. In other examples, the clearance distance is about 0.21 inch and the rotor support may have a height greater than 3 inches.

The groove distance, in some implementations, is equal to the greater of (a) one half of the inner diameter of one of the brake receiving surfaces, plus the clearance distance, and (b) a radius of the rotor support plus a threshold distance. The clearance distance may be about 0.18 inch, the threshold distance may be about 0.27 inch, and the rotor support may have a height of less than or equal to 3 inches, where the rotor support height measured as the overall height of the brake rotor minus the overall thickness of the braking band. In some examples, the clearance distance is about 0.21 inch, the threshold distance is about 0.35 inch, and the rotor support has a height greater than 3 inches.

Each groove path may extend along the at least one brake pad receiving surface at a threshold groove distance from the center axis greater than or equal to a radius of the rotor support plus a threshold distance. In some examples, the threshold distance is about 0.27 inch and the rotor support has a height of less than or equal to 3 inches. In additional examples, the threshold distance is about 0.35 inch and the rotor support has a height greater than 3 inches, where the rotor support height measured as the overall height of the brake rotor minus the overall thickness of the braking band. At least one groove may define a bull-nose shape in cross-section.

Another aspect of the disclosure provides a brake rotor that includes a rotor support and a braking band disposed on and encircling the rotor support. The braking band has first and second brake pad receiving surfaces on opposite sides of the braking band. At least one brake pad receiving surface defines groups of non-intersecting asymmetrical grooves. Each groove of each groove group has a groove path along the at least one brake pad receiving surface different from any other groove of the respective groove group and each groove of the respective groove group is arranged asymmetrically with respect to each other.

Implementations of the disclosure may include one or more of the following features. In some implementations, each groove group is arranged asymmetrically circumferentially about the at least one brake pad receiving surface. Each groove group may comprise first, second, and third grooves. Each groove is disposed in a respective first, second, and third groove region of the at least one brake pad receiving surface and arranged circumferentially with respect to each other about a center axis of rotation defined by the brake rotor. Each groove region may have a radial width of about ⅓ of a radial width of the at least one brake pad receiving surface. Moreover, each groove group can be sized to reside completely with a perimeter of an engagement surface of a received brake pad.

In some implementations, each groove path has first and second radii of curvature for corresponding first and second curves along the at least one brake pad receiving surface. The first and second radii of curvature may be equal.

The first and second brake receiving surfaces may each have inner and outer diameters with respect to a center axis of rotation of the brake rotor. Each groove path may extend along the at least one brake pad receiving surface at a groove distance from the center axis greater than or equal to one half of the inner diameter of the brake receiving surface having the largest inner diameter among the two brake receiving surfaces, plus a clearance distance.

In some examples, the clearance distance is about 0.18 inch and the rotor support has a height of less than or equal to 3 inches; while in other examples, the clearance distance is about 0.21 inch and the rotor support has a height greater than 3 inches. The rotor support height measured as the overall height of the brake rotor minus the overall thickness of the braking band.

The groove distance may be equal to the greater of (a) one half of the inner diameter of one of the brake receiving surfaces, plus the clearance distance, and (b) a radius of the rotor support plus a threshold distance. In some examples, the clearance distance is about 0.18 inch, the threshold distance is about 0.27 inch, and the rotor support has a height of less than or equal to 3 inches. In other examples, the clearance distance is about 0.21 inch, the threshold distance is about 0.35 inch, and the rotor support has a height greater than 3 inches.

In some implementations, each groove path extends along the at least one brake pad receiving surface at a threshold groove distance from the center axis greater than or equal to a radius of the rotor support plus a threshold distance. The threshold distance may be about 0.27 inch and the rotor support has a height of less than or equal to 3 inches. Alternatively, the threshold distance may be about 0.35 inch and the rotor support has a height greater than 3 inches. For each example, at least one groove may define a bull-nose shape in cross-section.

The details of one or more implementations of the disclosure are set forth in the accompanying drawings and the description below. Other aspects, features, and advantages will be apparent from the description and drawings, and from the claims.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial perspective view of a vehicle with an exemplary disc brake assembly.

FIG. 2A is a top view of an exemplary brake rotor.

FIG. 2B is a section view of the brake rotor shown in FIG. 2A along line 2B-2B.

FIG. 3A is a partial sectional view of an exemplary brake rotor.

FIG. 3B is a partial bottom view of the brake rotor shown in FIG. 3A along line 3B-3B.

FIG. 4 is a perspective view of an exemplary brake rotor receiving brake pads.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

Referring to FIGS. 1-3B, a brake rotor 100 for a disc brake assembly 20 for a vehicle 10 includes a mounting bell 110 for connection to a vehicle wheel hub 30 and a braking band 120 disposed on and encircling the mounting bell 110. The braking band 120 has first and second brake pad receiving surfaces 130, 140 on opposite sides of the braking band 120 for cooperating with and receiving brake pads 22 of calipers 24 of the disc brake assembly 20. The calipers 24 move the brake pads 22 between a first position disengaged from the brake receiving surfaces 130, 140 of the brake rotor 100 and a second position engaged with the brake receiving surfaces 130, 140 of the brake rotor 100, in order to exert a braking action on the vehicle 10. At least one of the brake pad receiving surfaces 130, 140 defines at least one groove 150 that has a groove path 152 extending along the respective brake pad receiving surfaces 130, 140. In the examples shown, both brake pad receiving surfaces 130, 140 include grooves 150.

In general, brakes convert friction to heat; however brakes that get too hot cease to work due to a failure to dissipate enough heat. This condition of failure is known as brake fade. The grooves 150 help prevent or decrease the likelihood of brake fade. In addition, the grooves 150 enable removal or drainage of accumulated water or moisture off of the brake receiving surfaces 130, 140 of the braking band 120, thus decreasing the presence of water between the brake pads 22 and the brake rotor 100 during passage of the brake rotor 100 through the calipers 24. Enhanced braking action is achieved by draining the water and moisture, via the grooves 150, off of the brake receiving surfaces 130, 140.

Referring to FIG. 2B, in some implementations, one or more grooves 150 have a variable depth d₁, d₂, d₃ with respect to the brake pad receiving surface 130, 140. Grooves 150 of variable depth provide full time out-gassing of friction volatiles and extended pad life (i.e., less pad wear over time) relative to rotors with constant depth grooves. In addition to extended wear life, the brake rotors 100 with variable depth grooves 150 facilitated relatively quicker vehicle stopping. Each groove 150 can define a particular cross-sectional shape, such as a bull-nose, rectangular, dovetail, trapezoid, etc.

Referring to FIG. 4, in some implementations, at least one brake pad receiving surface 130, 140 defines non-intersecting asymmetrical grooves 150 arranged asymmetrically with respect to each other. For example, each groove 150 can be arranged such that any line tangent 157 to the grove path 152 is at a different angle θ and/or distance from a longitudinal axis 101, a transverse axis 103, a center axis of rotation 105, any plane formed between the axes 101, 103, 105, and/or any other reference or datum with respect to the brake rotor 100. Moreover, each groove 150 can have a different geometry than every other groove 150. Each groove 150 may extend without a break in continuity having continuous walls that define the groove 150. Having non-intersecting grooves 150 allows for asymmetrical and/or random placement of the grooves 150 on the brake pad receiving surface 130, 140. For example, each groove 150 can be located without any pattern, such that the occurrence of one groove 150 in any given location at least one brake pad receiving surface 130, 140 has an equal probability of occurrence in another location on the at least one brake pad receiving surface 130, 140. A non-directional ripple style arrangement of grooves 150 (i.e., not necessarily systematically aligned or spaced with any predetermined reference, such as an axis or plan, or datum, such as a geometrical constraint or size, of the brake rotor 100) improves pad wear (i.e., less pad wear over time) as compared to rotors without such an arrangement of grooves. Moreover, in some implementations, each groove 150 has a non-linear groove path 152, as illustrated in FIG. 3B. Each groove path 152 may have first and second radii of curvature, R₁ and R₂, for corresponding first and second curves along the respective brake pad receiving surface 130, 140. The first and second radii of curvature R₁, R₂ can be equal or different. The curved groove paths 152 decrease brake pad wear relative to brake rotors without such grooves 150.

In some implementations, at least one brake pad receiving surface 130, 140 defines groups 160 of non-intersecting asymmetrical grooves 150. Each groove 150 of the groove group 160 has a respectively associated groove path 152 along the respective brake pad receiving surface 130, 140 different from any other groove 150 within the respectively associated groove group 160. Each groove group 160 may be arranged asymmetrically circumferentially about the respective brake pad receiving surface 130, 140. The asymmetrical grooves 150 and/or the asymmetrical arrangement of groove groups 160 about the brake pad receiving surface 130, 140 aids uniform wearing of the brake pad receiving surface 130, 140 over time and allows installation of the brake rotor 100 equally on right and left sides of the vehicle 10. Moreover, in some implementations, at least one groove group 160 can define a collective area 161 on the respective brake pad receiving surface 130, 140 around the constituent grooves 150 that has an area less than or equal to an engagement surface area 23 of a received brake pad 22, as shown in FIG. 4. Moreover, the collective area 161 may define a shape the same as or substantially similar to the engagement surface area 23 of the received brake pad 22. This helps maximize groove contact with a received brake pad 22 for out-gassing of friction volatiles.

Referring again to FIGS. 3A and 3B, in some implementations, each groove group 160 has one or more grooves 150 disposed in one or more groove regions 170 that encircle a mounting bell 110. For example, each groove group 160 can include first, second, and third grooves 150 a, 150 b, 150 c. Each groove 150 a, 150 b, 150 c resides in respective first, second, and third groove regions 170 a, 170 b, 170 c of the brake pad receiving surface 130, 140. The groove regions 170 a, 170 b, 170 c are arranged circumferentially about a center axis 105 which corresponds to the center of rotation of the brake rotor 100 when installed and functioning on a vehicle 10. In some examples, each groove region 170 a, 170 b, 170 c has a radial width W_(G) of about ⅓ of a radial width W_(S) of the respective brake pad receiving surface 130, 140.

The first and second brake receiving surfaces 130, 140 each have inner diameters D₁, D₂ and outer diameters D₃, D₄ with respect to the center axis of rotation 105 of the brake rotor 100. In some implementations, each groove path 152 extends along its respective brake pad receiving surface 130, 140 at a radial groove distance G (e.g., G₁, G₂, G₃ for each respective groove 150 a, 150 b, 150 c) from the center axis 105 greater than or equal to one half of the inner diameter D₁, D₂ of the brake receiving surface 130, 140 having the largest inner diameter D₁, D₂ among the two brake receiving surfaces 130, 140, plus a clearance distance C. This relationship is illustrated in equation 1, using a condition operator.

G≧(½ (IF D ₁ >D ₂ THEN D ₁, ELSE D ₂))+C  (1)

In some examples, the clearance distance C is about 0.18 inch and the mounting bell 110 has a height H_(B) of less than or equal to 3 inches. The mounting bell height H_(B) is measured as the overall height H_(All) of the brake rotor 100 minus the overall thickness T of the braking band 120. In other examples, the clearance distance C is about 0.21 inch and the mounting bell 110 has a height H_(B) greater than 3 inches.

The groove distance G may vary radially from a first end of a groove 150 to an opposite, second end of the groove 150. The groove distance G, in some implementations, is equal to the greater of (a) one half of the inner diameter D₁, D₂ of one of the brake receiving surfaces 130, 140 (such as the largest inner diameter D₁, D₂), plus the clearance distance C, and (b) a radius R_(B) of the mounting bell 110 plus a threshold distance M. The threshold distance M can be a minimum clearance distance between a groove 150 and the mounting bell 110. For example, the threshold distance M can be equal or greater than a tooling clearance in manufacturing the brake rotor 100. This relationship is illustrated in equation 2, using a condition operator.

G≧(IF a>b THEN a, ELSE b)  (2)

where a=(½ (IF D₁>D₂, THEN D₁, ELSE D₂))+C and b=R_(B)+M.

In some examples, the clearance distance C is about 0.18 inch, the threshold distance M is about 0.27 inch, and the mounting bell height H_(B) is less than or equal to 3 inches. In other examples, the clearance distance C is about 0.21 inch, the threshold distance M is about 0.35 inch, and the mounting bell height H is greater than 3 inches.

In yet further examples, each groove path 152 can extend along its respective brake pad receiving surface 130, 140 at the threshold groove distance G (e.g., G₁, G₂, G₃ for each respective groove 150 a, 150 b, 150 c) from the center axis 105 that is greater than or equal to the mounting bell radius R_(B) plus the threshold distance M. The threshold distance M can be about 0.27 inch for a mounting bell height H_(B) of less than or equal to 3 inches or the threshold distance M can be about 0.35 inch for a mounting bell height H_(B) greater than 3 inches.

A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. Accordingly, other implementations are within the scope of the following claims. 

What is claimed is:
 1. A brake rotor comprising: a rotor support; and a braking band disposed on and encircling the rotor support, the braking band having first and second brake pad receiving surfaces on opposite sides of the braking band, with at least one brake pad receiving surface defining a plurality of non-intersecting curvilinear asymmetrical grooves having groove paths extending along the at least one brake pad receiving surface, wherein the non-intersecting curvilinear asymmetrical grooves are arranged in groove groups of three grooves, with the groove groups are spaced from each other along the circumference of the at least one brake pad receiving surface.
 2. The brake rotor of claim 1, wherein the grooves are disposed in groove regions of concentric rings each having inner and outer circumferences with the groove regions arranged circumferentially about a center axis corresponding to the center of rotation of the brake rotor when installed and functioning on a vehicle.
 3. The brake rotor of claim 2, wherein, and wherein each groove region contains one or more grooves but no grooves extend from the inner circumference of an inner groove region ring to the outer circumference of an outer groove region ring.
 4. The brake rotor of claim 3, wherein three concentric rings are provided corresponding to innermost, central and outermost groove regions wherein no grooves extend from the inner circumference of the innermost groove region ring to the outer circumference of the central groove region ring, and no grooves extend from the inner circumference of the central groove region ring to the outer circumference of the outermost groove region ring.
 5. The brake rotor of claim 4, wherein each groove group has first, second, and third grooves disposed in the innermost, central and outermost groove regions, respectively.
 6. The brake rotor of claim 1, wherein each groove of a respective groove group has a groove path that is different from the other grooves of the respective groove group.
 7. The brake rotor of claim 1, wherein each groove of a respective groove group has a different geometry than the other grooves of the respective groove group.
 8. The brake rotor of claim 1, wherein each groove group is sized to reside completely within a perimeter of an engagement surface of a received brake pad.
 9. The brake rotor of claim 1, wherein at least 8 groove groups are provided in uniform spaced relation on the at least one brake pad receiving surface.
 10. The brake rotor of claim 1, wherein at least some of the grooves have variable depths with respect to the at least one brake pad receiving surface.
 11. The brake rotor of claim 1, wherein each groove in a groove group covers about ⅓ of a radial width of the at least one brake pad receiving surface.
 12. The brake rotor of claim 1, wherein at least one groove defines a bull-nose shape in cross-section.
 13. The brake rotor of claim 1, wherein the braking band is defined by a thickness dimension, wherein each groove is defined by a depth dimension, wherein the depth dimension is less than the thickness dimension.
 14. The brake rotor of claim 1, wherein the braking band is directly connected to and extends radially outwardly from the rotor support.
 15. The brake rotor of claim 1, wherein each groove is defined by a proximal end wall, a distal end wall, a first side wall and a second side wall, wherein the proximal end wall substantially directly opposes the distal end wall, wherein the first side wall substantially directly opposes the second side wall. 